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Abstract

This article investigates the chemical composition and properties of two compounds: sodium chlorate and 2-amino-1,3,4-thiadiazole. The physicochemical analytical methods used to study these compounds, including infrared (IR) spectroscopy, X-ray diffraction (XRD), and differential thermal analysis (DTA), are also discussed. The article also describes the processes of formation of new compounds based on these substances. The mass fraction of the new compound was determined using each element, and the theoretical and practical results were consistent. IR spectroscopic analysis revealed the presence of sodium chlorate and 2-amino-1,3,4-thiadiazole in the compound, and the bonds between them formed corresponding peaks at different energies. Data on the defoliant properties of the compound are presented, and agrochemical tests are conducted to evaluate its effectiveness as a complexing defoliant. The obtained data on the solubility and physicochemical properties of the new phase provide a fundamental basis for developing a technology for producing complex defoliants and physiologically active preparations based on sodium chlorate and thiadiazole derivatives. The aforementioned defoliants are based on heterocyclic compounds. In particular, XEF, thiazole, triazole, thiadiazole, and their derivatives are known to possess defoliant properties. Therefore, scientific research was conducted on the synthesis of highly effective defoliants by combining 2-amino-1,3,4-thiadiazole and chlorate defoliants from these heterocyclic compounds and the synthesis of a new type of complexing defoliant. A phase study of the system revealed the formation of a new individual chemical compound—an anhydrous molecular complex of the composition NaClO₃∙C₂H₃N₃S. The temperature and concentration limits of the stable existence of this phase were determined for the first time.

Аннотация

В данной статье исследуются химический состав и свойства двух соединений: хлората натрия и 2-амино-1,3,4-тиадиазола. Также обсуждаются физико-химические методы анализа, используемые для изучения этих соединений, включая инфракрасную (ИК) спектроскопию, рентгенофазовый анализ (РФА) и дифференциальный термический анализ (ДТА). В статье также описываются процессы образования новых соединений на основе этих веществ. Массовая доля нового соединения была определена с использованием каждого элемента, и теоретические и практические результаты оказались согласованными. ИК-спектроскопический анализ показал присутствие хлората натрия и 2-амино-1,3,4-тиадиазола в соединении, а связи между ними образовали соответствующие пики при разных энергиях. Представлены данные о дефолиантных свойствах соединения, а также проведены агрохимические испытания для оценки его эффективности в качестве комплексодействующего дефолианта. Полученные данные о растворимости и физико-химических свойствах новой фазы являются фундаментальной основой для разработки технологии получения комплексных дефолиантов и физиологически активных препаратов на основе хлората натрия и производных тиадиазола. Основой вышеупомянутых дефолиантов являются гетероциклические соединения. В частности, известно, что XEF, тиазол, триазол, тиадиазол и их производные обладают дефолиантными свойствами. Поэтому были описаны научные исследования по синтезу высокоэффективных дефолиантов путем сочетания 2-амино-1,3,4-тиадиазола и хлоратных дефолиантов из этих гетероциклических соединений и синтеза нового типа комплексодействующего дефолианта. В ходе фазового изучения системы выявлено образование нового индивидуального химического соединения — безводного молекулярного комплекса состава NaClO₃∙C₂H₃N₃S. Впервые определены температурные и концентрационные границы устойчивого существования данной фазы.

Keywords: 2-amino-1,3,4-thiadiazole, sodium chlorate,  IR-spectroscopy, X-ray phase analysis (XRPA),  including infrared (IR) spectroscopy, differential thermal analysis (DTA).

Ключевые слова: 2-амино-1,3,4-тиадиазол, хлорат натрия, ИК-спектроскопия, рентгенофазовый анализ (РФА), включая инфракрасную (ИК) спектроскопию, дифференциальный термический анализ (ДТА).

Introduction

Since the world's population is increasing day by day, the full satisfaction and rational use of human needs for drinking water, rural agriculture and food is one of the important issues of the present day [1]. To do this, it is possible to achieve a solution to part of this problem by developing rural enemas, especially by increasing the cultivation of cotton. Currently, the Independent Republic of Uzbekistan ranks fifth in the world in terms of cotton cultivation, with an annual production of 1.5 million grows more than a ton of cotton fibers [2]. Of the agrotechnical measures in the quality cultivation of cotton fiber – defoliation, it is considered one of the necessary measures [3].

Defoliants used for this are required to be obtained on the basis of cheap, harmless, not adversely affecting the environment, and especially on the basis of maximal raw materials. This, in turn, ensures that the crop is harvested quickly and qualitatively on time, without leaving it for rainy days [4]. After defoliation, light falls between the rows, heat and air circulation improves, as a result of which the formation and opening of the breasts is accelerated. Due to defoliation, the productivity of cotton harvest work increases and the fulfillment of the above requirements is achieved [5]. Therefore, the implementation of the production of cheap, harmless, environmentally friendly defoliers in the Republic of Uzbekistan is now very relevant [6].

Currently, in our Republic, mainly sodium chlorate, calcium chlorate and magnesium chlorates are synthesized, and on their basis, defoliants such as “Uzdef”, “Sixat”, “Sadaf”, “Morel”, “Super xmd” and “Polidef” are widely used. However, these defoliants do not fully comply with the current requirements. Therefore, the need to synthesize defoliants with complex effects is emerging [7].

It is known from the literature that defoliants obtained on the basis of organic matter have much higher efficiency [8]. For example, the composition of “Butibos”, “Tsitodef”, “ Dropp”, “Dropp-ultra”, “hydrel”, “dihydrel”, “gemetrel” and many defoliants are mainly organic substances, these defoliants are produced in foreign countries and are partially used in the Agriculture of our Republic [9,10].

The basis of the defoliants named above are heterocyclic compounds. It is especially known that thiazole, triazole, thiadiazole and their derivatives have the property of defolicity [11,12]. Therefore, scientific research has been described on the synthesis of efficacious defoliants by combining 2-amino-1,3,4-thiadiazole and chlorate defoliants from these heterocyclic compounds together to synthesize new types of complex-acting defoliants [13-16].

Materials and methods

The heterocyclic compound is 2-amino-1,3,4-thiadiazole and sodium chlorate, chemical and physico-chemical analysis methods (IR-spectroscopic analysis method, XRPA and DTA).

Main part: this article is devoted to the synthesis of complex-acting defioliers with high efficiency, based on inorganic and heterocyclic compounds.

2-amino-1,3,4– thiadiazole is an OK-yellow crystalline substance, molecular weight - 101.15; density -1.385 g/cm³, solubility at 20°C - 25 mg/ml, liquefaction temperature – 191-192°C [17,18].

To study the element composition of 2-amino-1,3,4-thiadiazole, the X-ray-phase (XPA) analysis method determined the elemental composition (Figure 1).

Figure 1. XPA Element Analysis of 2 - amino –1,3,4 – thiadiazole

Based on the theoretical and practical analyses conducted, it can be concluded that, according to the results of the analysis, the substance in question corresponds to 2-amino-1,3,4-thiadiazole [19].

Table 1. Chemical composition of 2-amino-1,3,4-thiadiazole

Results and discussion

Incorporating The resulting derivatogram, presented in the figure, consists of three curves. The dynamic thermogravimetric analysis (DTGA) curve (curve 2) shows that the decomposition process occurs mainly within two temperature ranges. The decomposition temperature of 2-amino-1,3,4-thiadiazole is 115 °C. The first decay interval corresponds to the temperature range from 117 to 305 °C, while the second decay interval is from 312 to 704 °C.

Figure 2. The derivative of 2-amino-1,3,4-thiadiazole and its differential thermal analysis (TGA, DTA).

In this study, the dynamic thermal analysis (DTA) consists of three curves. The Dynamic DTA (Curve 2) analysis reveals that the DTA curve is primarily realized in two intensively decomposing temperature ranges. Within the 1st decay range, an intense decay process takes place, and during this range, 68.81% of the decay occurs. A detailed analysis of the dynamic curves, listed in Table 2, provides further insight.

Based on these findings from DTA studies, it is notable that the majority of mass loss occurs within the 115-720 °C range, where 99.84% of the initial mass is lost.

Table 2. Analysis of DTGA and DSC curve results of 2-amino-1,3,4-thiadiazole

Sodium chlorate (NaClO₃) is a white, colorless, crystalline powder that is highly soluble in water. It is hygroscopic and a strong oxidizing agent, decomposing at temperatures above 300°C to release oxygen and leave sodium chloride. The solubility of sodium chlorate in water is 79.6 grams in 0°C and 204 grams in 100°C. Its spatial structure is prismatic or cuboidal [20].

To carry out the study, 2-amino-1,3,4-thiadiazole (organic heterocyclic compound) was weighed at 40 g and dissolved in 200 ml of 96% ethanol. Aqueous solution of sodium chlorate (NaClO₃) was weighed at 40 g on top of the ethanol solution. The aqueous solution of NaClO₃ was dissolved in 100 g of water. In a mole ratio of 1:1, the NaClO₃ solution was added to the 2-amino-1,3,4-thiadiazole ethanol solution and the reaction was conducted at 40–50 °C for 2 h. The reaction proceeded as follows:

C₂H₃N₃S + NaClO₃ + H₂O → C₂H₃N₃S ∙ NaClO₃+ H₂O

The final solution environment was maintained at pH-6.1 and cooled to room temperature. After filtering, the solution was crystallized and the resulting crystals were further filtered.

The synthesized compound was characterized using chemical, infrared spectroscopic (IR), XRPA (X-ray phase analysis), and DTA (differential thermal analysis) methods.

Chemical analysis of chlorate salt crystals containing 2-amino-1,3,4-thiadazole was conducted using an energy-dispersive X-ray fluorescence spectrometer (model Rigaku NexDE VS from Japan). The findings are presented in Figure 4 and Table 3.

Figure 3. Chemical analysis of the product obtained from NaClO₃ and 2-amino-1,3,4-thiadiazole

In this experiment, we conducted a chemical analysis to determine the composition of elements present in the resulting compound. The results are presented in Table 3 below.

Table 3. Chemical analysis results for the compound formed from the reaction between chlorate salt and 2-amino-1,3,4-thiadiazole

The results of the chemical analysis conducted using the Perkin Elmer FT-IR/NIR spectrometer are presented for the composition analysis of the substance based on sodium chlorate and 2-amino - 1,3,4-thiadiazole. The samples were analyzed using a range of ATR systems and a film. An IR-spectrum was generated in the range of 4000 to 400 cm⁻¹. The samples were prepared by covering a KBr pellet with the matrix for analysis.

The obtained results are shown in Figures 4 and 5, as well as in Tables 4a and 4b. The results indicate the formation of C₂H₄N₂SClO₃ salt. The IR-spectrum of the mixture of NaClO₃ and 2-amino-1,3,4-thiadiazole reveals the presence of hydrogen bonds and specific vibration modes associated with the 2-amino-1,3,4-thiadiazole ring.

Figure 4. IR-spectrum: 2-amino -1,3,4 - chlorate salt of thiadiazole

Strong peaks in the low-frequency region indicate interactions between components of the mixture and changes in the crystal lattice of the NaClO₃ salt. The presence of weak and uncharacteristic peaks indicates the formation of a chlorate salt of 2-amino-1,3,4-thiadiazole in the mixture, as described above.

Table 4. The distribution of the chlorate salt of 2-amino-1,3,4-thiadiazole and (a), 2-amino-1,3,4-thiadiazole by functional groups (b)

To study the element composition of the chlorate salt of 2-amino -1,3,4 - thiadiazole, the elemental composition of the new compound was determined by the method of X-ray analysis. The results obtained are shown in Figure 6.

Figure 5. X-ray analysis of chlorate salt of 2-amino -1,3,4-thiadiazole

The elementary composition and mass shares of the new compound based on NaClO₃ and 2-amino -1,3,4 - thiadiazole are given in Table 5.

The molar mass of the mahuslot formed when the percentage composition of the elements given below is calculated based on 171 grams/ mol, while the molar mass of sodium chlorate is 106.5 g/mol and the molar mass of 2-amino-1,3,4-thiadiazole is 101 g/mol. It follows from this that there is a mass loss in the middle. It has been found that this mass loss is mainly due to the leakage of gases.

From the results obtained, it can be concluded that the results of chemical analysis with XRPA analysis are almost similar, i.e. show that 2-amino-1,3,4-thiadiazole corresponds to the chlorate salt.

Table 5. The theoretical and practical elementary composition and mass shares of the chlorate salt of 2-amino-1,3,4-thiadiazole

Differential thermal analysis (DTA) of the compound formed from the chlorate salt of the newly formed 2-amino-1,3,4-thiadiazole has been studied. The results obtained are shown in Figure 6 and Table 6.

Figure 6. NaClO₃ and 2-amino are derivatives of the product from 1,3,4-thiadiazole. Differential thermal analysis (TGA, DTA)

The product's decomposition temperature obtained from the interaction of NaClO₃ and 2-amino-1,3,4-thiadiazole is 97 °C. In this case, the decay process is divided into two stages: the first takes place in the temperature range from 117 to 305 °C, and the second - from 312 to 704 °C.

The figure shows three curves: 1 is the dynamic thermogravimetric analysis curve (DTGA); 2 is the derivative of this curve (DTGP); 3 is the DSK curve. The analysis of these curves allows us to conclude that the most active decay process is observed in the first temperature range, reaching a value of 49.44% of the total decay level.

The table below provides a detailed analysis of the dynamic thermogravimetric analysis and DSK curves.

Differential thermal analysis shows that the bulk of the product is lost in the temperature range from 113 to 547 °C, accounting for 55.09% of the total mass. These data indicate that the reaction results in the formation of the sodium salt of 2-amino-1,3,4-thiadiazole.

Table 6. The results of the determination of DTGA and DSC chlorate salt of 2-amino-1,3,4-thiadiazole, which was obtained from 2-amino-1,3,4-thiadiazole and sodium chlorate

2-amino-1,3,4-thiadiazole and 2-amino-1,3,4-thiadiazole, synthesized on the basis of sodium chlorate by the above experimental methods, were separated from the chlorate salt of thiadiazole 200 gr crystal and given to agrochemical testing. The chlorate salt of 2-amino-1,3,4-thiadiazole synthesized in it showed a mild effect on cotton, leaf deposition was above 90%, and opening of cotton cobs was 93-94%.

Conclusion

This paper synthesizes the chlorate salt of 2-amino-1,3,4-thiadiazole, a heterocyclic compound, and 2-amino-1,3,4-thiadiazole based on sodium chlorate. The mass shares of the resulting new compound were determined by each element, with theoretically derived composition (%): O-30.76; Cl-20.06; Na-11.05; C-11.53; H-0.9% and practical derived composition: O-28.8; Cl-21.3; Na-13.8; C-11.4; H-0.7%. This suggests that 2-amino-1,3,4-thiadiazole is compatible with chlorate salt. In addition the IR-spectroscopic analysis method has also been found to produce the presence of elements in the chlorate salt of 2-amino-1,3,4-thiadiazole and the corresponding peaks in the different energies of the bonds contained. The chlorate salt of this 2-amino-1,3,4-thiadiazole has been agrochemically tested as a new type of complex-acting defoliant and has been found to be highly effective.

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